A typical motor vehicle includes several light producing elements that are adapted to provide exterior illumination and/or to increase the visibility of the vehicle to others. These light producing elements include, for example, headlights, taillights, and daytime running lamps. A typical vehicle's lighting system includes these and other light producing elements, a lighting controller, an ambient light sensor, and a user interface. The lighting controller is adapted to cause the light producing elements to turn on and off (e.g., to put the light producing elements in an activated state (on) or a deactivated state (off)).
The user interface of the lighting system (e.g., a multi-setting knob on the dashboard or on the turn signal lever) typically includes settings that allow a user manually to turn the headlights on and off, and also that allow the user to set the lighting system into an automatic control mode. While in the automatic control mode, the lighting controller automatically determines when to activate or deactivate the headlights based on the ambient light conditions of the exterior surroundings. The ambient light conditions may be detected by the ambient light sensor, which provides information regarding the ambient light conditions to the lighting controller.
The daytime running lamps (DRLs) may be controlled in coordination with the headlights, and the DRLs may make it easier for others to notice the vehicle at times when the headlights are in a deactivated state. In some vehicles, the DRLs are distinct light producing elements from the headlights. In other vehicles, the headlights may be considered to be DRLs when they are operated at a reduced intensity level from the normal headlight intensity level. While the lighting system is set in the automatic control mode, the DRLs may be activated (or the intensity of the headlights may be reduced to the DRL intensity level) at times when the headlights are in a deactivated state. Alternatively, the DRLs may be deactivated (or the intensity of the headlights may be increased to the normal headlight intensity level) at times when the headlights are in an activated state.
DRLs tend to be the most effective as a safety device during low ambient light conditions, such as at dawn, at dusk, and when the vehicle is in dark shadow or darkness (e.g., in a tunnel or parking structure). When the vehicle is in bright ambient light conditions and, thus, is more highly visible, the safety benefits of the DRLs are less likely to be realized. However, as long as the lighting system is set in the automatic control mode, the DRLs will remain activated in such bright ambient light conditions (i.e., when the headlights are deactivated). Thus, even when their safety benefits are less likely to be realized, the DRLs continue to consume on-board electrical power. The power consumption of the DRLs may decrease the vehicle's fuel economy.
Societal trends are moving toward more energy-efficient products in many product sectors, with a particular emphasis on producing more energy-efficient motor vehicles (e.g., motor vehicles with improved fuel economy). Accordingly, what are needed are more energy-efficient, motor vehicle lighting systems and methods for their operation. Other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.